Inpatient aggression on mental health wards is common and staff–patient interactions are frequently reported antecedents to aggression. However, relatively little is known about the precise relationship between aggression and these interactions, or their relationships with aggression and staff containment responses such as restraint and seclusion. This study aimed to determine the roles of anger and interpersonal style among mental health nurses and between nurses and patients in the occurrence of aggression and its containment. A correlational, pseudoprospective study design was employed. n = 85 inpatients and n = 65 nurses were recruited from adult, low- and medium-secure wards of a secure forensic mental health service. Participants completed validated self-report anger and transactional interpersonal style measures. Inpatient aggression and containment incident data for a 3-month follow-up period were extracted from clinical records. Dyadic nurse–patient relationships were anticomplementary. Patients' self-reported anger and staff-rated hostile interpersonal style were significantly positively correlated; staff self-reported anger and patient-rated dominant interpersonal style were also positively correlated. Patient anger predicted aggression and their interpersonal style predicted being subject to containment in the form of restraint and seclusion. There were no statistically significant differences identified on measures between staff who were and were not involved in containment. More targeted intervention for patients' anger may have a positive impact on interpersonal style and lead to the reduction of incidents. Staff education and skills training programmes should emphasize the importance of interpersonal styles which could help to promote and enhance positive interactions.